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    <title>Document</title>
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    <script>
      let hd = 'houdunren2200hdcms998';
      // let nums = [...hd].filter((item) => !Number.isNaN(parseInt(a)));

      console.log(hd.match(/\d/g).join(''));

      let hd1 = 'houdunren.com';
      console.log(/u/g.test(hd1));

      let a = 'u';
      console.log(eval(`/${a}/`).test(hd));

      let url = 'https://www.houdunren.com';
      console.log(/https?:\/\/\w+\.\w+\.\w+/.test(url));
    </script>
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